Lechoslaw Lomozik

Complexes of copper(II) with spermine and non-covalent interactions in the systems including nucleosides or nucleotides

Abstract Taking into account a change in the acid-base properties of metal-free systems of spermine (Spm) and nucleoside (Nuc) or nucleotide (NMP), appearing as a result of non-covalent interactions between the bioligands, the composition of the molecular complexes formed and their overall stability constants were determined. The centres of ion–dipole interactions were established to be protonated amine groups of Spm and the nitrogen donor atoms of nucleosides as well as the phosphate residues and the nitrogen donor atoms of nucleotides. A distinct difference was found between the behavior of adenosine monophosphate and cytidine monophosphate. The presence of at least two reaction centers in the majority of relatively stable adducts was found which emphasizes the role of spatial arrangement in the species. The assumed model of interactions is supported by the fact that molecular complex formation is observed in the pH range of nucleoside or nucleotide deprotonation and polyamine protonation. The co-ordination nature of spermine in the systems with Cu(II) differs from that of polyamines of shorter chains. The stability constants of the mixed-ligand complexes formed, their stochiometry and mode of co-ordination were determined (the main co-ordination sites are the nucleotide phosphate residues as well as N(1) and N(7) atoms of purine or N(3) of pyrimidine rings). The interactions in nucleoside-containing systems are, however, essentially different from those in the systems which comprise nucleotides. The formation of Cu(AMP)H x (Spm) and Cu(CMP)H x (Spm) adducts, in which copper ions were coordinated only via oxygen atoms of phosphate groups, was established. In the case of nucleoside-containing systems, it was found that Cu(Nuc)(Spm) mixed-ligand complexes with a chromophore of N5-type are formed.

Interactions in binary and ternary systems including Cu(II), uridine, uridine 5′-monophosphate or diamine

Abstract Results of equilibrium and spectral studies have shown that, in the systems of uridine (Urd) or uridine 5′-monophosphate (UMP) with the diamines (PA) ethylenediamine, 1,3-diaminopropane or putrescine, molecular complexes of the type (Urd)Hx(PA) and (UMP)Hx(PA) are formed. Overall stability constants of the adducts and equilibrium constants of their formation have been determined. The tendency towards complex formation increases with growing length of the PA. The pH range of adduct formation is found to coincide with that in which the PA is protonated, whereas Urd or its monophosphate is deprotonated. The NH3+ groups from PA and N(3) atoms and phosphate groups from the nucleosides have been identified as the centres of non-covalent interactions. Overall stability constants of the Cu(II) complexes with Urd and UMP have been determined. It was found that, in the Cu(Urd)+ and Cu(Urd)(OH)x complexes, the reaction of metallation mainly involves N(3) atoms from the pyrimidine bases. Results of the spectral and equilibrium studies of the Cu/UMP system indicate coordination involving the N(3) atom and the phosphate groups from UMP, whereas in the complexes Cu(UMP)(OH)x, appearing at high pH, the involvement of the N(3) atom has been excluded and the main sites of metallation are oxygen atoms from carbonyl groups, besides those from hydroxyl groups. The mode of coordination of Cu(II) complexes with Urd or UMP, including diamines, was also determined.

A study of polyamine complex formation with H+, Cu(II), Zn(II), Pb(II), and Mg(II) in aqueous solution

SummaryThe composition and stability of the following biogenic amine complexes have been investigated: 1,4-diaminobutane(Put), 4-azaoctane-1,8-diamine(Spd), 4,9-diazadodecan-1, 12-diamine(Spm) as well as homologues such as 1,3-diaminopropane(Put3), 4-azaheptane-1, 7-diamine(Spd3,3) and 4,8-diazaundecan-1,11-diamine(Spm3,3,3) with H+, Cu(II), Zn(II), Pb(II) and Mg(II). A potentiometric method was used. The VIS technique enabled the determination of coordination mode in copper/amine systems. It was found that Mg(II) does not form coordination compounds with any of the studied polyamines in solution. An increase in the concentration of ligand and metal was found to result in a stronger tendency towards the formation of protonated compounds accompanied by a decrease in the concentration of hydroxocomplexes. At physiologicalpH (7.4) an increase in the concentration of protonated compounds by approximately 15% was observed within the ligand concentration range from 0.001 mol dm−3 to 0.0001 mol dm−3 at a Cu(II) concentration of 0.000177 mol dm−3.ZusammenfassungAnhand einer Analyse von potentiometrischen Daten wurden Zusammensetzung und Beständigkeit folgender biogener Aminkomplexe untersucht: 1,4-Diaminobutan(Put), 4-Azaoktan-1,8-diamin(Spd), 4,9-Diazadodekan-1,12-diamin(Spm), sowie auch deren Homologen 1,3-Diaminopropan(Put3), 4-Azaheptan-1,7-diamin(Spd3,3) und 4,8-Diazaundekan-1,11-diamin(Spm3,3,3) mit H+, Cu(II), Zn(II), Pb(II) und Mg(II). Mit Hilfe der VIS-Technik wurde die Koordinationsweise in Kupfer/Amin-Systemen bestimmt. Es wurde festgestellt, daß Mg(II) keine Koordinationsverbindungen mit den untersuchten Polyaminen bildet. Eine höhere Konzentration von Ligand und Metall führte zu stärkerer Tendenz der Bildung protonierter Verbindungen, wobei die Konzentration von Hydroxokomplexen kleiner wurde. Bei physiologischempH (7.4) wurde im Bereich der Ligand-Konzentration von 0.001 mol dm−3 bis 0.0001 mol dm−3 bei einer Cu(II)-Konzentration von 0.000177 mol dm−3 ein Anstieg der Konzentration protonierter Verbindungen um etwa 15% beobachtet.

Copper(II) ions as a factor interfering in the interaction between bioligands in systems with adenosine and polyamines

Abstract Noncovalent interactions were found to occur in metal-free adenosine-polyamine systems. Overall stability constants and equilibrium constants of the reaction of adduct formation were determined. The ranges in which the adducts occur overlap with the ranges in which nucleoside is deprotonated while polyamine is protonated. Stability constants and complex distribution in the ternary Cu/Ado/PA (PA = polyamine) systems were also identified. The coordination mode in the studied complexes in solution was determined. Unlike in 1,3-diaminopropane (tn), putrescine (Put), and 1,7-diamino-4-azaheptane (3,3-tri), in the systems containing spermidine (Spd), the coordination dichotomy between the N(1) and N(7) atoms of nucleoside was observed to disappear. In some complexes occurring in the systems with tn, 3,3-tri (but not with Put and Spd), a coordination with nitrogen atoms at axial position was detected in solution. Generally, however, a tendency to form square-planar structures dominates. Differences in the coordination mode of complexes in solution and solid complexes were determined.

Investigations of binding sites and stability of complexes formed in ternary Cu(II)/adenosine or cytidine/putrescine systems

Abstract In the adenosine-putrescine (1,4-diaminobutane) system, noncovalent interaction between bioligands was found to occur. The equilibrium constant of the adduct formation reaction is equal to log K = 1.51. The ligand-ligand interaction is not observed to occur in the cytidine/putrescine system. On the basis of computer analysis of potentiometric titration data for ternary systems: Cu(II)/adenosine (or cytidine)/putrescine, the stability constants of the complexes were determined and their distribution was presented. It was found that in the cytidine-containing systems, mixed-ligand complexes are not formed. Spectral studies indicate characteristic differences in the mode of coordination in the adenosine ternary systems relative to binary systems. A presence of putrescine contributes to the broadening (relative to the Cu(II)/Ado binary system) of pH range for the coordination dichotomy to occur. Differences in the coordination mode between the synthesized solid complexes and complexes in solution have been identified. Likewise in solution, cytidine does not form solid mixed-ligand complexes with Cu(II) and putrescine.

Mode of coordination and stability of Cu(II) and Zn(II) complexes with adenosine, deoxyadenosine, cytidine and deoxycytidine

SummaryStability constants of Cu(II) and Zn(II) complexes with nucleosides have been determined from a computer analysis of potentiometric titration results. Spectral investigations prove that in acidic solution adenosine coordinates to Cu(II)via its N1 or N7 atoms, while atpH>7 only N7 is involved. Similar interactions are observed for dAdo complexes. Spectral and potentiometric studies suggest that Zn does not form stable complexes with dAdo. In the case of cytidine and deoxycytidine, the preferred site of coordination is the N3 atom of the nucleoside. Oxygen atoms from the carbonyl groups are not involved in Cu(II) or Zn(II) coordination. The results of the spectral investigation have excluded the ribose and deoxyribose moieties of all studied ligands from participation in the interactions. In general, the mode of coordination of nucleosides and deoxynucleosides with Cu(II) and Zn(II) has been found analogous.ZusammenfassungMittels einer Computeranalyse von Ergebnissen aus potentiometrischen Titrationen wurden Stabilitätskonstanten für Komplexe aus Cu(II) bzw. Zn(II) und Nucleosiden bestimmt. Spektroskopische Untersuchungen zeigen, daß Adenosin in saurer Lösung über N1 oder N7 an Cu(II) koordinieren kann, während beipH>7 nur N7 reagiert. Analoges wird für die Komplexe mit dAdo beobachtet. Aus spektroskopischen und potentiometrischen Untersuchungen geht hervor, daß Zn mit dAdo keine stabilen Komplexe bildet. Im Fall von Cytidin und Deoxycytidin ist N3 die bevorzugte Koordinationsstelle des Nucleosids. Die Sauerstoffatome der Carbonylgruppen sind an der Bindung an Cu(II) und Zn(II) nicht beteiligt. Die spektroskopischen Ergebnisse schließen eine Beteiligung der Ribose- und Deoxyriboseeinheiten an den Wechselwirkungen aus. Allgemein wurde für Nucleoside und Deoxynucleoside ein analoger Koordinationsmodus gefunden.

Intermolecular and coordination reactions in the systems of copper(II) with adenosine 5′-monophosphate or cytidine 5′-monophosphate and triamines

Formation of molecular complexes as a result of non-covalent interactions between adenosine 5-monophosphate (AMP) or cytidine 5-monophosphate (CMP) and polyamines, 1,5-diamino-3-azapentane (dien) or 1,6-diamino-3-azahexane (2,3-tri), has been studied in metal-free systems. Based on the acid–base equilibrium changes, the composition and stability constants of the molecular complexes formed have been determined. Spectral analysis has revealed that the interaction centers in these adducts are protonated amine groups from the polyamine, phosphate groups and donor nitrogen atoms from the nucleotide. In the ternary systems of Cu(II) with AMP or CMP and polyamines, dien or 2,3-tri, the composition and stability constants of the heteroligand complexes formed have been determined. The presence of the following complexes has been detected: Cu(CMP)(dien), Cu(AMP)(dien), Cu(CMP)(2,3-tri), Cu(CMP)(2,3-tri)(OH). Results of the equilibrium and spectral studies (Vis, IR, EPR, 13 C, 31 P NMR) have shown that in the mixed complexes, all nitrogen atoms from the polyamine and oxygen atoms from the phosphate group of the nucleotide take part in the coordination. The donor nitrogen atoms N(1) and N(7) from AMP and N(3) from CMP are in the outer coordination sphere.

Spectroscopic and potentiometric investigation of the solution structure and stability of Ni(II) and Co(II) complexes with adenosine 5′-monophosphate and 1,12-diamino-4,9-diazadodecane (spermine) or 1,11-diamino-4,8-diazaundecane

Abstract The solution structures of nickel(II) and cobalt(II) mixed-ligand complexes with adenosine 5′-monophosphate and tetramines have been found. The nickel(II) ions were proved to coordinate the nitrogen atoms N(1) and N(7) from the nucleotide forming chromophore {N1} in the molecular complexes of type ML·····L′ and chromophore {N3} in the protonated complexes. In the mixed-ligand complexes with nickel(II) ions, a coordination dichotomy N1/N7 was observed. In the mixed complexes with cobalt(II) ions, the presence of a chromophore {N1,O}, with N(7) nitrogen atom and oxygen atoms from the AMP phosphate group, was found. On the other hand, in molecular complexes the non-covalent interactions between the totally protonated polyamine and nucleotide atoms of high electron density were established. The presence of interligand non-covalent interactions, additionally stabilising the complex, was discovered in the species Ni(AMP)H2(Spm). Results of the equilibrium study for the species Ni(AMP)H2(3,3,3-tet) indicated that only one nitrogen atom from the polyamine was involved in the coordination.

Equilibrium and spectral studies of putrescine complexes with copper(II)

SummaryIt has been found that in the putrescine-copper system several types of complex compounds (MHL,ML,ML2,ML2OH) are formed. In thepH range of 7–9, despite a multiple excess of ligand, a precipitation occurs. When adenosine is introduced to the system, the ability to observe the complexation reaction in solution is largely increased, because the additional ligand prevents precipitation. On the basis of computer analysis of potentiometric titration data the stability constants of the compounds have been determined. The coordination mode of the complexes is discussed.ZusammenfassungEs wurde festgestellt, daß sich im Putrescin-Kupfer System einige Typen von Komplexen bilden (MHL,ML,ML2 andML2OH). ImpH-Bereich von 7–9 tritt trotz eines mehrfachen Ligandenüberschusses ein Niederschlag auf. Bei Einführung von Adenosin in das System wird die Beobachtbarkeit der Komplexreaktion verbessert, da der zusätzliche Ligand die Niederschlagsbildung verhindert. Mittels Computeranalyse der potentiometrischen Titrationsdaten wurden die Stabilitätskonstanten der Verbindungen ermittelt. Die Art der Komplexierung wird ebenfalls diskutiert.

Crystal and molecular structures of cadmium(II) nitrate complexes with triamines: 1,5-diamino-3-azapentane, 1,6-diamino-3-azahexane and 1,7-diamino-4-azaheptane

The following new complexes of Cd(II) nitrate with triamines have been prepared and characterized: [Cd(NH 2 (CH 2 ) 2 NH(CH 2 ) 2 NH 2 ) 2 ](NO 3 ) 2 ( 1 ), [Cd(NH 2 (CH 2 ) 2 NH(CH 2 ) 3 NH 2 ) 2 ](NO 3 ) 2 ( 2 ) and [Cd(NH 2 (CH 2 ) 3 NH(CH 2 ) 3 NH 2 ) 2 ](NO 3 ) 2 ( 3 ). Their structures have been determined by a single-crystal X-ray diffraction method. Because of the instability of the crystals 2 and 3 at room temperature, all complexes were examined at 100 K. In the complexes investigated all nitrogen atoms of the triamines coordinate the Cd(II) atom. All data sets showed {N6}-coordinated complexes. The stoichiometry of the complexes in the solid state is always 1:2, although the crystals were grown from solutions with different concentration ratios of the components (Cd–triamine: 1:1, 1:2 or 1:3). The Cd(II) atom of complex 1 is sandwiched between two triamines related by a twofold axis. Complexes 2 and 3 are characterized by a distorted octahedral coordination. The conclusions obtained correspond to the solution structures obtained from NMR, IR as well as equilibrium studies.